net/sched/act_sample.c

   1 /*
   2  * net/sched/act_sample.c - Packet sampling tc action
   3  * Copyright (c) 2017 Yotam Gigi <yotamg@mellanox.com>
   4  *
   5  * This program is free software; you can redistribute it and/or modify
   6  * it under the terms of the GNU General Public License version 2 as
   7  * published by the Free Software Foundation.
   8  */
   9
  10 #include <linux/types.h>
  11 #include <linux/kernel.h>
  12 #include <linux/string.h>
  13 #include <linux/errno.h>
  14 #include <linux/skbuff.h>
  15 #include <linux/rtnetlink.h>
  16 #include <linux/module.h>
  17 #include <linux/init.h>
  18 #include <linux/gfp.h>
  19 #include <net/net_namespace.h>
  20 #include <net/netlink.h>
  21 #include <net/pkt_sched.h>
  22 #include <linux/tc_act/tc_sample.h>
  23 #include <net/tc_act/tc_sample.h>
  24 #include <net/psample.h>
  25
  26 #include <linux/if_arp.h>
  27
  28 static unsigned int sample_net_id;
  29 static struct tc_action_ops act_sample_ops;
  30
  31 static const struct nla_policy sample_policy[TCA_SAMPLE_MAX + 1] = {
  32         [TCA_SAMPLE_PARMS]              = { .len = sizeof(struct tc_sample) },
  33         [TCA_SAMPLE_RATE]               = { .type = NLA_U32 },
  34         [TCA_SAMPLE_TRUNC_SIZE]         = { .type = NLA_U32 },
  35         [TCA_SAMPLE_PSAMPLE_GROUP]      = { .type = NLA_U32 },
  36 };
  37
  38 static int tcf_sample_init(struct net *net, struct nlattr *nla,
  39                            struct nlattr *est, struct tc_action **a, int ovr,
  40                            int bind)
  41 {
  42         struct tc_action_net *tn = net_generic(net, sample_net_id);
  43         struct nlattr *tb[TCA_SAMPLE_MAX + 1];
  44         struct psample_group *psample_group;
  45         struct tc_sample *parm;
  46         struct tcf_sample *s;
  47         bool exists = false;
  48         int ret;
  49
  50         if (!nla)
  51                 return -EINVAL;
  52         ret = nla_parse_nested(tb, TCA_SAMPLE_MAX, nla, sample_policy, NULL);
  53         if (ret < 0)
  54                 return ret;
  55         if (!tb[TCA_SAMPLE_PARMS] || !tb[TCA_SAMPLE_RATE] ||
  56             !tb[TCA_SAMPLE_PSAMPLE_GROUP])
  57                 return -EINVAL;
  58
  59         parm = nla_data(tb[TCA_SAMPLE_PARMS]);
  60
  61         exists = tcf_idr_check(tn, parm->index, a, bind);
  62         if (exists && bind)
  63                 return 0;
  64
  65         if (!exists) {
  66                 ret = tcf_idr_create(tn, parm->index, est, a,
  67                                      &act_sample_ops, bind, true);
  68                 if (ret)
  69                         return ret;
  70                 ret = ACT_P_CREATED;
  71         } else {
  72                 tcf_idr_release(*a, bind);
  73                 if (!ovr)
  74                         return -EEXIST;
  75         }
  76         s = to_sample(*a);
  77
  78         s->tcf_action = parm->action;
  79         s->rate = nla_get_u32(tb[TCA_SAMPLE_RATE]);
  80         s->psample_group_num = nla_get_u32(tb[TCA_SAMPLE_PSAMPLE_GROUP]);
  81         psample_group = psample_group_get(net, s->psample_group_num);
  82         if (!psample_group) {
  83                 if (ret == ACT_P_CREATED)
  84                         tcf_idr_release(*a, bind);
  85                 return -ENOMEM;
  86         }
  87         RCU_INIT_POINTER(s->psample_group, psample_group);
  88
  89         if (tb[TCA_SAMPLE_TRUNC_SIZE]) {
  90                 s->truncate = true;
  91                 s->trunc_size = nla_get_u32(tb[TCA_SAMPLE_TRUNC_SIZE]);
  92         }
  93
  94         if (ret == ACT_P_CREATED)
  95                 tcf_idr_insert(tn, *a);
  96         return ret;
  97 }
  98
  99 static void tcf_sample_cleanup_rcu(struct rcu_head *rcu)
 100 {
 101         struct tcf_sample *s = container_of(rcu, struct tcf_sample, rcu);
 102         struct psample_group *psample_group;
 103
 104         psample_group = rcu_dereference_protected(s->psample_group, 1);
 105         RCU_INIT_POINTER(s->psample_group, NULL);
 106         if (psample_group)
 107                 psample_group_put(psample_group);
 108 }
 109
 110 static void tcf_sample_cleanup(struct tc_action *a, int bind)
 111 {
 112         struct tcf_sample *s = to_sample(a);
 113
 114         call_rcu(&s->rcu, tcf_sample_cleanup_rcu);
 115 }
 116
 117 static bool tcf_sample_dev_ok_push(struct net_device *dev)
 118 {
 119         switch (dev->type) {
 120         case ARPHRD_TUNNEL:
 121         case ARPHRD_TUNNEL6:
 122         case ARPHRD_SIT:
 123         case ARPHRD_IPGRE:
 124         case ARPHRD_VOID:
 125         case ARPHRD_NONE:
 126                 return false;
 127         default:
 128                 return true;
 129         }
 130 }
 131
 132 static int tcf_sample_act(struct sk_buff *skb, const struct tc_action *a,
 133                           struct tcf_result *res)
 134 {
 135         struct tcf_sample *s = to_sample(a);
 136         struct psample_group *psample_group;
 137         int retval;
 138         int size;
 139         int iif;
 140         int oif;
 141
 142         tcf_lastuse_update(&s->tcf_tm);
 143         bstats_cpu_update(this_cpu_ptr(s->common.cpu_bstats), skb);
 144         retval = READ_ONCE(s->tcf_action);
 145
 146         rcu_read_lock();
 147         psample_group = rcu_dereference(s->psample_group);
 148
 149         /* randomly sample packets according to rate */
 150         if (psample_group && (prandom_u32() % s->rate == 0)) {
 151                 if (!skb_at_tc_ingress(skb)) {
 152                         iif = skb->skb_iif;
 153                         oif = skb->dev->ifindex;
 154                 } else {
 155                         iif = skb->dev->ifindex;
 156                         oif = 0;
 157                 }
 158
 159                 /* on ingress, the mac header gets popped, so push it back */
 160                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 161                         skb_push(skb, skb->mac_len);
 162
 163                 size = s->truncate ? s->trunc_size : skb->len;
 164                 psample_sample_packet(psample_group, skb, size, iif, oif,
 165                                       s->rate);
 166
 167                 if (skb_at_tc_ingress(skb) && tcf_sample_dev_ok_push(skb->dev))
 168                         skb_pull(skb, skb->mac_len);
 169         }
 170
 171         rcu_read_unlock();
 172         return retval;
 173 }
 174
 175 static int tcf_sample_dump(struct sk_buff *skb, struct tc_action *a,
 176                            int bind, int ref)
 177 {
 178         unsigned char *b = skb_tail_pointer(skb);
 179         struct tcf_sample *s = to_sample(a);
 180         struct tc_sample opt = {
 181                 .index      = s->tcf_index,
 182                 .action     = s->tcf_action,
 183                 .refcnt     = s->tcf_refcnt - ref,
 184                 .bindcnt    = s->tcf_bindcnt - bind,
 185         };
 186         struct tcf_t t;
 187
 188         if (nla_put(skb, TCA_SAMPLE_PARMS, sizeof(opt), &opt))
 189                 goto nla_put_failure;
 190
 191         tcf_tm_dump(&t, &s->tcf_tm);
 192         if (nla_put_64bit(skb, TCA_SAMPLE_TM, sizeof(t), &t, TCA_SAMPLE_PAD))
 193                 goto nla_put_failure;
 194
 195         if (nla_put_u32(skb, TCA_SAMPLE_RATE, s->rate))
 196                 goto nla_put_failure;
 197
 198         if (s->truncate)
 199                 if (nla_put_u32(skb, TCA_SAMPLE_TRUNC_SIZE, s->trunc_size))
 200                         goto nla_put_failure;
 201
 202         if (nla_put_u32(skb, TCA_SAMPLE_PSAMPLE_GROUP, s->psample_group_num))
 203                 goto nla_put_failure;
 204         return skb->len;
 205
 206 nla_put_failure:
 207         nlmsg_trim(skb, b);
 208         return -1;
 209 }
 210
 211 static int tcf_sample_walker(struct net *net, struct sk_buff *skb,
 212                              struct netlink_callback *cb, int type,
 213                              const struct tc_action_ops *ops)
 214 {
 215         struct tc_action_net *tn = net_generic(net, sample_net_id);
 216
 217         return tcf_generic_walker(tn, skb, cb, type, ops);
 218 }
 219
 220 static int tcf_sample_search(struct net *net, struct tc_action **a, u32 index)
 221 {
 222         struct tc_action_net *tn = net_generic(net, sample_net_id);
 223
 224         return tcf_idr_search(tn, a, index);
 225 }
 226
 227 static struct tc_action_ops act_sample_ops = {
 228         .kind     = "sample",
 229         .type     = TCA_ACT_SAMPLE,
 230         .owner    = THIS_MODULE,
 231         .act      = tcf_sample_act,
 232         .dump     = tcf_sample_dump,
 233         .init     = tcf_sample_init,
 234         .cleanup  = tcf_sample_cleanup,
 235         .walk     = tcf_sample_walker,
 236         .lookup   = tcf_sample_search,
 237         .size     = sizeof(struct tcf_sample),
 238 };
 239
 240 static __net_init int sample_init_net(struct net *net)
 241 {
 242         struct tc_action_net *tn = net_generic(net, sample_net_id);
 243
 244         return tc_action_net_init(tn, &act_sample_ops);
 245 }
 246
 247 static void __net_exit sample_exit_net(struct net *net)
 248 {
 249         struct tc_action_net *tn = net_generic(net, sample_net_id);
 250
 251         tc_action_net_exit(tn);
 252 }
 253
 254 static struct pernet_operations sample_net_ops = {
 255         .init = sample_init_net,
 256         .exit = sample_exit_net,
 257         .id   = &sample_net_id,
 258         .size = sizeof(struct tc_action_net),
 259 };
 260
 261 static int __init sample_init_module(void)
 262 {
 263         return tcf_register_action(&act_sample_ops, &sample_net_ops);
 264 }
 265
 266 static void __exit sample_cleanup_module(void)
 267 {
 268         rcu_barrier();
 269         tcf_unregister_action(&act_sample_ops, &sample_net_ops);
 270 }
 271
 272 module_init(sample_init_module);
 273 module_exit(sample_cleanup_module);
 274
 275 MODULE_AUTHOR("Yotam Gigi <yotam.gi@gmail.com>");
 276 MODULE_DESCRIPTION("Packet sampling action");
 277 MODULE_LICENSE("GPL v2");